D1 -> D2

[Walter Bright]

Steven Schveighoffer wrote:
> My recommendation -- when you are ready, switch wholly to D2.  Don't 
> bother with compatibility, it's just not possible.

 From what you wrote, it appears that most of the difficulties were in dealing 
with strings. Might I suggest:

1. Replace all occurrences of char[] with string.

2. Compile to find every place that mutable strings are used.

3. Refactor the code to clearly encapsulate where mutable strings are created 
and manipulated, and as the last step, cast them to string.